Many fungal secondary metabolites such as antibiotics, are of industrial interest. Numerous fungal secondary metabolites have beneficial biological activities that can be used in the medical field, including antibiotics and antitumor drugs. Other fungal products, such as mycotoxin, are detrimental for human and animal health and negatively impact agriculture causing economic losses. Overexpression of the gene mtfA enhances production of fungal compounds with applications in the medical field, and overexpression or impaired mtfA expression decreases the production of compounds such as mycotoxins that negatively affect health/agriculture/economy.
Species of the genus Aspergillus produce numerous secondary metabolites, including compounds with beneficial effects, such as antibiotics and other molecules with application in the medical field. Aspergillus nidulans, a model filamentous fungus studied for more than fifty years, produces the mycotoxin sterigmatocystin (ST). ST and the carcinogenic compounds called aflatoxins (AF), produced by related species such as A. flavus, A. parasiticus, and A. nomiusi are both synthesized through a conserved metabolic pathway where ST is the penultimate precursor. The genes responsible for ST/AF biosynthesis are clustered. Within the clusters, the regulatory gene aflR encodes a transcription factor that acts as a specific cluster activator.
Aspergillus nidulans also produces the beta-lactam antibiotic penicillin and the antitumoral compound terraquinone.
In fungi secondary metabolism, regulation is often found to be governed by genetic mechanisms also controlling asexual and sexual development. One of the main common regulatory links is the global regulatory gene veA, described to be a developmental regulator in A. nidulans. The connection between veA and the synthesis of numerous secondary metabolites, including ST was described. Absence of the veA gene in A. nidulans prevents OR expression and ST biosynthesis. VeA also regulates the production of other metabolites, including penicillin. In other fungi, veA homologs also regulate the synthesis of penicillin in Penicillium chrysogenum as well as cephalosporin C in Acremonium chrysogenum. Furthermore, veA also regulates the biosynthesis of other mycotoxins, for example AF, cyclopiazonic acid and aflatrem in Aspergillus flavus, trichothecenes in F. graminerum, and fumonisins and fusarins in Fusarium spp, including F. verticillioides and F. fujikuroi. 
veA is extensively conserved in Ascomycetes. Most of the studies on the veA regulatory mechanism of action have been carried out using the model fungus A. nidulans. It is known that KapA α-importin transports the VeA protein to the nucleus, particularly in the dark, a condition that favors ST production. In the nucleus, VeA interacts with several proteins such as the light-responsive protein FphA, which interacts with the LreA-LreB. FphA, LreA and LreB also have influence fungal development and mycotoxin production. While FphA negatively regulates sexual development and the synthesis of ST, the LreA and LreB proteins play the opposite role. In the nucleus VeA also interacts with VelB and LaeA. LaeA, a chromatin-modifying protein is also required for the synthesis of ST and other secondary metabolites. Deletion of velB decreased and delayed ST production, indicating a positive role in ST biosynthesis.
In addition to its role as global regulator of development and secondary metabolism, VeA is also required for normal plant pathogenicity by several mycotoxigenic species, such as A. flavus, F. verticillioides F. fujikuroi, and F. graminearum. Deletion of veA homologs in these organisms results in a decrease in virulence with a reduction in mycotoxin biosynthesis.